I need help on a big decesion!?

When I get out of high school I am wanting to go into the military. I have narrowed it down to the Marine Corp and the Army. When I get of the military I am wanting a job in law enforcement such as the CIA, FBI, or NSA. I don't know what job I need to do in the military when I get their that would help me in a future career in one of these agencies, and idk if I need to do special forces either, please help I appreciate it.